Since its inception decades ago, optical fibers have typically been designed and manufactured using an approach that involves a thin strand of glass comprised of a single, solid glass core in which the light signals propagate, encapsulated by a glass cladding layer with a different refractive index that helps keep the light within the core during transmission. Along the way, optical fiber has incurred many iterations of positive advancements, resulting in the fibers we have today that efficiently deliver data at unprecedented levels in a low-loss, low-latency manner.
However, as data demands continue to soar currently in 2024 and are expected to continue this upward trajectory for the foreseeable future, leading fiber manufacturers have been working on several new designs intended to increase capacity, reduce latency, or both. The two types that appear to be showing the most promise for optical fibers in terms of viability are Hollow-Core Optical Fiber (HCF) and Multicore Optical Fiber (MCF), so far demonstrating some real improvements in speed, bandwidth, and capacity.
Let’s take a brief look at both types of fiber, including their technical composition and primary performance benefits, along with a few examples of the fiber brands and companies at the forefront of these innovation efforts.
Hollow-Core Optical Fiber (HCF)
Hollow Core Optical Fiber, as its name implies, is a type of optical fiber in which the core is hollow and comprised of air rather than solid glass. This unique structural design approach significantly alters the fiber's light propagation properties, enabling several performance advantages over conventional fibers with solid glass cores.
HCF Benefits and Applications
There are a few technical advantages that can be realized by utilizing an optical fiber that enables transmitted light signals to travel through air instead of glass.
Companies Leading Hollow Core Fiber Innovation
While still in the early stages of the technology lifecycle, a few well-known companies have been at the forefront of developing high-performance hollow-core optical fibers for network and data center applications.
Note: These major entities are not the only companies that manufacture hollow-core fibers, as there are several other entities (ex: ThorLabs, NKT Photonics, etc) that offer HCF for specialized communications.
Multicore Optical Fiber (MCF)
Based on the design concept of Space Division Multiplexing (SDM), Multicore Optical Fiber is a type of fiber that consists of multiple cores within a single strand of fiber. Each core operates independently, allowing multiple data streams to be transmitted simultaneously through the single fiber. This physical multiplexing capability using multiple cores significantly enhances the data capacity of each fiber, as a 2-core MCF essentially delivers twice the amount of data as a single-core fiber, and so on.
MCF Benefits and Applications
Companies Leading Multicore Fiber Innovation
Like HCF fibers, multicore fibers are still in the development infancy period, but there are several examples of prominent companies aiming to make a splash which include:
Note: Other companies in this arena that also offer multicore fiber include Fibercore and iXblue, as just a few additional examples.
The Future of HCF and MCF – A Look Ahead
While it is unlikely that traditional single-core optical fibers will go away any time soon, both hollow-core and multicore optical fibers appear to represent the exciting next generation of optical fiber innovation, especially for meeting the demands of faster, more efficient, and higher-capacity networks. With key players in the industry like Sumitomo®, OFS®, and Microsoft® making significant investments into further developing these specialty fibers and already noting real deployments in the data center and financial trading arenas, that future is already here.
It will be interesting to see the direction of HCF and MCF design and production over time, as many questions still currently remain in terms of their outlook. What will the global demand picture look like for both types of fiber in the long run? Will they ultimately replace traditional single-core fibers to a major degree across entire networks or will their use be limited to more specific areas or applications? Will service providers prioritize latency advantages and skew more towards HCF or capacity increases and skew more towards MCF?
On the manufacturing side of things, the competitive landscape is always changing. Which ones will be able to successfully leverage their resources and expertise to achieve performance advantages along with mass-producing the fiber reliably and cost-effectively? What technical and manufacturing hurdles will they need to overcome? Will Microsoft® eventually make its HCF available to the larger market or keep its use internal and/or for select business cases? Will OFS® and Sumitomo® establish themselves as market leaders for their respective fibers due to their early-mover progress?
It should also be noted that the name of one key player, arguably the largest and most influential company to pioneer and produce optical fiber, has not yet been mentioned - Corning®. As of the date of this article, Corning® has yet to make any public announcements in terms of HCF or MCF development or production efforts. However, always at the scientific forefront of new fibers with an eye on the future, it will be interesting to see if, when, and how they make an impact with these fiber types or if they pioneer an alternative approach entirely.
One thing is certain – the future is bright for the development of new optical fibers for high-bandwidth, low-latency networks. At this juncture, the same can be said for both hollow-core and multicore technology, which are demonstrating performance benefits that align with future data delivery needs and expectations.
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If you would like to learn more about hollow-core and multicore fibers, or you require custom lengths of these fibers for network and latency simulation testing or optical time delay applications, contact M2 Optics at your convenience.